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Center for Cognitive Health

Intermittent Fasting, Could It Help Protect Your Brain While Aging?

Why do people get Alzheimer’s disease (AD)?

The cause of this disease is still widely unknown, but after many years of studying AD caloric intake, neuroscience professor Mark Mattson suggests that it may have to do with our modern eating habits. Mattson is particularly focused on the timing and frequency of our meals and how this affects our brains. 

Intermittent fasting, also known as caloric restriction, may not just be a tool used to achieve weight loss goals. When you adopt intermittent fasting into your lifestyle, you are cycling through short periods of eating and longer periods of fasting.

Historically, humans would naturally fast in between periods of hunting and gathering foods, as food was not as accessible as it is today.  Stocked kitchens and pantries allow us easier access to food at any hour of the day, and early breakfasts and late-night snacking have made it harder for humans to achieve our natural fasting state. This hinders the body’s ability to metabolically switch from using glycogen to ketones for fuel.

Glycogen is derived from the glucose in carbohydrates that we eat and is used as fuel for up to 12 hours after we eat. If we don’t use all our glycogen between meals it is turned to fat. Ketones are derived from our fat reserves and take over after the glycogen is all used up. Fasting shifts our energy production from glycogen to ketones.

Both glycogen and ketones fuel our neurons, but higher ketone production has been linked to improvements in thinking, learning, and memory. 

Fasting is quickly showing strong potential for the treatment of AD as it has been shown to slow cognitive decline and improve AD symptoms in mice. In several studies, researchers used genetically altered mice displaying AD symptoms. The mice that were fed on an intermittent fasting diet were better off than those that were allowed to eat whenever they wanted. The fasting mice showed better cognitive functioning and had less plaque buildup in their brains. They also lived longer than the mice that were not fasting.

Fasting can also lower oxidative stress. Oxidative stress occurs when we breakdown the food we eat to utilize the energy from the sun.  Unfortunately, the very process that keeps us alive, accessing the sun’s energy from our food via free radical formation, damages our cellular function as we age and contributes to the development of Alzheimer’s disease and the aging process — the more we eat the more we rust! Fasting upregulates free radical scavengers and anti-oxidants.

Diets that are high in simple sugars are associated with an increased risk for developing AD, the worst being refined sugar. Currently there are several clinical trials studying the link between nutrition and neurodegenerative diseases as there is still much to be learned about caloric restriction as a form of treatment or prevention. 

Managing caloric intake reduces body fat mass and provides other age-related benefits such as supporting healthy weight loss which, in a recent clinical trial, was associated with cognitive improvement in elderly individuals with Mild Cognitive Impairment (MCI).

Does this mean you should immediately start fasting?

Until more is known about the effectiveness of intermittent fasting in the prevention of AD, the best thing to do is to reconsider those late night snacks and limit your eating to about 12 hours a day, making sure to fast for the other 12 hours. If this 12/12 regime is not unpleasant for you, attempt a 16/8 fasting regime in which you skip breakfast, having only tea or coffee without sugar, and stop eating dinner at 8:00pm.  A regimen such as this can help protect your brain as you age and make other positive contributions to your overall health. One of the worst things you can do is eat a large dinner and then go right to sleep, so make sure to stop taking in calories about 3 hours before bedtime. 

The following video features professor Mark Mattson discussing theories and findings related to intermittent fasting and the benefits it can have when adopted into your lifestyle.

The Growing Science Behind a Fasting Treatment for Alzheimer’s [Internet]. The Crux. 2019. Available from: http://blogs.discovermagazine.com/crux/2019/06/19/the-growing-science-behind-a-fasting-treatment-for-alzheimers/#.XUsdlfJKgdU
Markesbery WR. The Role of Oxidative Stress in Alzheimer Disease [Internet]. Archives of Neurology. American Medical Association; 1999. Available from: https://jamanetwork.com/journals/jamaneurology/fullarticle/775665